The present application is related, generally and in various embodiments, to a miniaturized multichannel wireless telemetry system. More particularly, the present application relates to a miniaturized multichannel wireless telemetry system for biopotential monitoring.
Neurophysiological investigations of function require the collection of biophysical parameters in unrestrained animals. Conventional techniques involve wire connections and restraint tethering which limit animal movement and recording conditions. Although the use of various wireless telemetry systems have been previously proposed, the systems suffer various shortcomings and limitations.
Some multichannel telemetry systems use sequential conversion of input signals to a current to control a current-controlled oscillator based upon a monolithic chip. The monolithic chip has an overall size of approximately 3 mm×3 mm, is all complementary bipolar (BJT), and contains a single set of amplifiers, reference circuits and a CCO (current controlled oscillator). The overall package size of these systems, not including the battery, is often relatively large, thereby precluding use in small animals. For example, the overall package size of one of these systems was approximately 3.8 cm×2.7 cm×0.8 cm. The systems also lack clocking provisions, and require the addition of commercial CMOS chips. Other limitations include an inability for preamplification, buffering, filtering, or providing proper input impedance.
Other multichannel telemetry systems utilize time-sharing sequential multiplexing. However, the overall size of the systems, not including the battery, are still relatively large and are designed for signals such as strain gauges or EKG rather than weaker signals such as EEG and EMG. For example, the overall size of one of these systems was approximately 8 cm×2 cm×1 cm.
Other multichannel telemetry systems utilize a miniaturized EEG transmitter, measuring approximately 1.95 cm×1.6 cm×0.63 cm. The EEG transmitters used in these systems typically include tightly packed discrete components that are difficult to assemble. One such EEG transmitter is adapted to be anchored to the skull of a small animal and includes two asymmetric channels, but lacks remote on/off capability. Another such EEG transmitter includes four single-ended channels, rather than differential channels.